Automatic detection of potential merge errors

ABSTRACT

In an approach to detection of potential merge errors when merging source code, a computer detects a source code merge process start. The computer compares at least one change made to a main stream of source code to a child stream. The computer determines whether one or more of the at least one change made to the main stream are not included in the child stream. Responsive to determining one or more of the at least one change made to the main stream are not included in the child stream, the computer determines the one or more of the at least one change made to the main stream that are not included in the child stream were removed from the child stream during a software development activity. The computer flags one or more files of the child stream corresponding to the one or more of the at least one change.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of version controlsystems for software development, and more particularly to automaticdetection of potential merge errors in source code.

Source code is any collection of computer instructions (possibly withcomments) written using some human-readable computer language, often astext. The source code of a program is specially designed to facilitatethe work of computer programmers, who specify the actions to beperformed by a computer by writing source code. The source code is oftentransformed by a compiler program into low-level machine code understoodby the computer. The machine code may then be stored for execution at alater time. Alternatively, an interpreter can be used to analyze andperform the outcomes of the source code program directly on the fly. Thesource code which constitutes a program is often held in one or moretext files stored on a computer's hard disk; these files may becarefully arranged into a directory tree, known as a source tree. Sourcecode can also be stored in a database (as is common for storedprocedures) or elsewhere.

In the field of software development, revision control is a practicethat tracks and provides control over changes to collections ofinformation such as source code, documentation, or configuration files.Within software development projects, development teams often leveragefeatures of revision control systems to practice various forms ofbranching. Branching is a mechanism for isolation and paralleldevelopment of software applications. A “branch” is a line ofdevelopment of an application or system, which exists independent ofanother line of development, yet shares a common history. A branch maybe a copy of some existing version, release, task, component, etc., ofan application. A branch may be, for example, a new release, a new task,a new architectural component, a new version, or another differentiatingaspect of an application. Certain branches are created with theintention of eventually merging somewhere at a future time.

A merge or integration is an operation in which two sets of changes areapplied to a file or set of files. Merging two files can be a delicateoperation, and may only be possible if the data structure is simple, asin text files. The result of a merge of two image files may not resultin an image file at all. A second developer checking in code needs totake care with the merge, to make sure that the changes are compatibleand that the merge operation does not introduce its own logic errorswithin the files. For example, a branch is created, the code in thefiles is independently edited, and the updated branch is laterincorporated into a single, unified trunk.

SUMMARY

Embodiments of the present invention disclose a method, a computerprogram product, and a system for detection of potential merge errorswhen merging source code. The method may include one or more computerprocessors detecting a source code merge process start. The one or morecomputer processors compare at least one change made to a main stream ofsource code to a first child stream, where the first child stream is anincoming child stream of source code, and where the at least one changewas made between a time corresponding to a branching of the first childstream and a time of the merge process start. The one or more computerprocessors determine whether one or more of the at least one change madeto the main stream of source code are not included in the first childstream. In response to determining one or more of the at least onechange made to the main stream of source code are not included in thefirst child stream, the one or more computer processors determinewhether the one or more of the at least one change made to the mainstream of source code that are not included in the first child streamwere removed from the first child stream during a software developmentactivity. In response to determining the one or more of the at least onechange made to the main stream of source code that are not included inthe first child stream were not removed from the first child streamduring a software development activity, the one or more computerprocessors flag one or more files of the first child streamcorresponding to the one or more of the at least one change.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram illustrating a distributed dataprocessing environment, in accordance with an embodiment of the presentinvention;

FIG. 2 is a flow diagram illustrating version control activities duringa software development project, in accordance with an embodiment of thepresent invention;

FIG. 3 is a flowchart depicting operational steps of a merge errordetection program, on a server computer within the distributed dataprocessing environment of FIG. 1, for detection of source code mergeissues, in accordance with an embodiment of the present invention; and

FIG. 4 depicts a block diagram of components of the server computerexecuting the merge error detection program within the distributed dataprocessing environment of FIG. 1, in accordance with an embodiment ofthe present invention.

DETAILED DESCRIPTION

Many source control or version control systems are based on the conceptof streams. A main/trunk stream contains the base copy of the sourcecode for the software being developed. Child streams are branched offthe main stream for development in isolation, and are then merged backinto the main stream when development is complete. On occasion, a filemay be modified on both streams. This may require the developer torebase the child stream, to get the latest changes from the main stream,and merge any files that were modified by both streams before the childstream is merged back into the main stream.

Embodiments of the present invention recognize that the risk ofunintentional changes being introduced to the main source stream duringa stream merge may be reduced by automatically detecting potential mergeissues or errors during the merging of source code streams. Embodimentsof the present invention also recognize that time and resources spentidentifying and resolving unintentional code changes that are introducedto the main source stream by merge activities may be reduced byautomatically detecting potential merge issues during the merging ofsource code streams. Implementation of embodiments of the invention maytake a variety of forms, and exemplary implementation details arediscussed subsequently with reference to the Figures.

FIG. 1 is a functional block diagram illustrating a distributed dataprocessing environment, generally designated 100, in accordance with oneembodiment of the present invention. The term “distributed” as used inthis specification describes a computer system that includes multiple,physically distinct devices that operate together as a single computersystem. FIG. 1 provides only an illustration of one implementation anddoes not imply any limitations with regard to the environments in whichdifferent embodiments may be implemented. Many modifications to thedepicted environment may be made by those skilled in the art withoutdeparting from the scope of the invention as recited by the claims.

Distributed data processing environment 100 includes client computingdevice 104 and server computer 108, interconnected over network 102.Network 102 can be, for example, a telecommunications network, a localarea network (LAN), a wide area network (WAN), such as the Internet, ora combination of the three, and can include wired, wireless, or fiberoptic connections. Network 102 can include one or more wired and/orwireless networks that are capable of receiving and transmitting data,voice, and/or video signals, including multimedia signals that includevoice, data, and video information. In general, network 102 can be anycombination of connections and protocols that will supportcommunications between client computing device 104, server computer 108,and other computing devices (not shown) within distributed dataprocessing environment 100.

Client computing device 104 can be a laptop computer, a tablet computer,a smart phone, or any programmable electronic device capable ofcommunicating with various components and devices within distributeddata processing environment 100, via network 102. In general, clientcomputing device 104 represents any programmable electronic device orcombination of programmable electronic devices capable of executingmachine readable program instructions and communicating with othercomputing devices (not shown) within distributed data processingenvironment 100 via a network, such as network 102. Client computingdevice 104 includes user interface 106.

User interface 106 provides an interface between a user of clientcomputing device 104 and server computer 108. In one embodiment, userinterface 106 may be a graphical user interface (GUI) or a web userinterface (WUI) and can display text, documents, web browser windows,user options, application interfaces, and instructions for operation,and include the information (such as graphic, text, and sound) that aprogram presents to a user and the control sequences the user employs tocontrol the program. In another embodiment, user interface 106 may alsobe mobile application software that provides an interface between a userof client computing device 104 and server computer 108. Mobileapplication software, or an “app,” is a computer program designed to runon smart phones, tablet computers and other mobile devices. Userinterface 106 enables a user of client computing device 104 to accessserver computer 108 for software development activities.

Server computer 108 can be a standalone computing device, a managementserver, a web server, a mobile computing device, or any other electronicdevice or computing system capable of receiving, sending, and processingdata. In other embodiments, server computer 108 can represent a servercomputing system utilizing multiple computers as a server system, suchas in a cloud computing environment. In another embodiment, servercomputer 108 can be a laptop computer, a tablet computer, a netbookcomputer, a personal computer (PC), a desktop computer, a personaldigital assistant (PDA), a smart phone, or any programmable electronicdevice capable of communicating with client computing device 104 andother computing devices (not shown) within distributed data processingenvironment 100 via network 102. In another embodiment, server computer108 represents a computing system utilizing clustered computers andcomponents (e.g., database server computers, application servercomputers, etc.) that act as a single pool of seamless resources whenaccessed within distributed data processing environment 100. Servercomputer 108 includes version control software 110. Server computer 108may include internal and external hardware components, as depicted anddescribed in further detail with respect to FIG. 4.

Version control software 110 is one of a plurality of software programsdesigned to manage changes or revisions to documents, computer programs,large web sites, and other collections of information. Version controlsoftware 110 may provide features for tracking, managing, and/orimplementing changes to source code files and for generating (orbuilding) one or more versions of a product. As a component of asoftware configuration management package, version control software 110generally identifies changes by a number or letter code, termed the“revision number,” “revision level,” or simply “revision.” In computersoftware engineering, version control, or revision control, is any kindof practice that tracks and provides control over changes to sourcecode. Version control software 110 may maintain one or more log filesthat list and describe each change to the base source code. A log filemay detail each change by file name and line number. Software developersmay use version control software 110 to maintain documentation andconfiguration files as well as source code. Version control software 110includes version control database 112, merge error detection program114, main code stream 116, and child code stream 118.

Version control database 112 is a repository for code changes managed byversion control software 110. A database is an organized collection ofdata. Version control database 112 can be implemented with any type ofstorage device capable of storing data and configuration files that canbe accessed and utilized by server computer 108, such as a databaseserver, a hard disk drive, or a flash memory. Version control database112 may store attributes associated with a code change such as the nameof the developer that made the change, the date the change was made, thepurpose of the change, and any detected errors associated with thechange.

Merge error detection program 114 flags software development activitiesin a child stream at the time of delivery to the main stream which mayhave errors as a result of a merge of changes from the main stream tothe child stream. In the depicted embodiment, merge error detectionprogram 114 is integrated into version control software 110. In anotherembodiment, merge error detection program 114 may be a standaloneprogram. As a standalone program, merge error detection program 114 canreside on server computer 108 or elsewhere in distributed dataprocessing environment 100, provided that version control software 110has access to merge error detection program 114. Merge error detectionprogram 114 automatically detects potential merge issues during themerging of source code streams. In order to automatically detectpotential merge errors, as a merge process begins, merge error detectionprogram 114 compares change sets for files in the main stream to theincoming child stream, starting from the point in time when the childstream was branched off or since the child stream was last successfullymerged with the main stream. If any changes in the main stream are notincluded in the child stream, then merge error detection program 114determines whether missing changes were removed intentionally. If mergeerror detection program 114 determines the changes were not removedintentionally, then merge error detection program 114 determines whetherthere are any un-reviewed activities in the child stream that containthe file with the missing changes. If there are un-reviewed activities,then merge error detection program 114 flags the file and/or activitiesassociated with the changes such that a software developer can reviewthe changes, rectify any errors, and manually re-start the mergeprocess. Merge error detection program 114 is depicted and described infurther detail with respect to FIG. 3.

Main code stream 116 is an example of source code which a user of clientcomputing device 104 is changing. Main code stream 116 may be referredto as a “trunk” of the source code. Source code is any collection ofcomputer instructions written using some human-readable computerlanguage. The source code of a program is specially designed tofacilitate the work of computer programmers, who specify the actions tobe performed by a computer by writing source code. The source code isoften transformed by a compiler program into low-level machine codeunderstood by the computer. Child code stream 118 is a branch of maincode stream 116. In an embodiment, child code stream 118 may be one ormore of a plurality of child code streams. A “branch” is a line ofdevelopment of an application or system, which exists independent ofanother line of development, yet shares a common history. Child codestream 118 begins as a copy of main code stream 116. Child code stream118 may be, for example, a new release, a new task, a new architecturalcomponent, a new version, or another differentiating aspect of main codestream 116. In one embodiment, main code stream 116 and child codestream 118 reside in version control database 112.

FIG. 2 is flow diagram 200 illustrating version control activitiesduring a software development project, in accordance with an embodimentof the present invention. Main code stream 116, as discussed withrespect to FIG. 1, is represented by the large arrow going from left toright, and is depicted with events that occur through time. Child codestream 118, as discussed with respect to FIG. 1, is represented by thesmaller arrow going from left to right, and is depicted with events thatoccur through time. Event 202 is the point in time where child codestream 118 is branched off of main code stream 116. At the time thatchild code stream 118 is branched off of main code stream 116, the twocode streams are identical.

Shortly after event 202, software development activity 204 begins inchild code stream 118, where a software developer is making changes toFile A. Sometime later, software development activity 206 begins in maincode stream 116, where a software developer is also making changes toFile A. Periodically during the development of child code stream 118,version control software 110 performs a rebase operation to sync changesthat have been made to main code stream 116 with child code stream 118.The rebase operation may be automatic, or it may be triggered by asoftware developer working on child code stream 118. Just before mergingchild code stream 118 back into main code stream 116, version controlsoftware 110 causes rebase 208 to occur. During rebase 208, child codestream 118 pulls in any changes that have been made to main code stream116 since child code stream 118 branched off or since child code stream118 was last successfully merged with main code stream 116. Rebase 208may occur automatically, or version control software 110 may prompt auser to trigger rebase 208. Next, as merge changes 210 begins,modifications made to File A in software development activity 206 aremerged into File A in child code stream 118. Merge changes 210 may bedone manually, by a software developer, or automatically, by versioncontrol software 110. In the example, changes to File A from softwaredevelopment activity 206 are unintentionally removed during mergechanges 210.

Version control software 110 attempts a stream merge at event 212 tomerge child code stream 118 into main code stream 116. Merge errordetection program 114 detects the start of a merge process and comparesthe change sets in main code stream 116 to child code stream 118 sincechild code stream 118 branched off or since child code stream 118 waslast successfully merged with main code stream 116. Merge errordetection program 114 determines that changes to File A in main codestream 116 from software development activity 206 are missing in childcode stream 118.

In a first example, merge error detection program 114 determines thatthe changes were not intentionally removed from File A in child codestream 118 because the deletion of the changes was not part of softwaredevelopment activity 204 or any other non-merge activity on child codestream 118 since child code stream 118 branched off or since child codestream 118 was last successfully merged with main code stream 116. Sincethe missing changes were not intentionally removed from child codestream 118, merge error detection program 114 detects a merge error.Merge error detection program 114 creates flag 214 to indicate thatthere is a potential merge error in File A. In one embodiment, if morethan one software development activity in child code stream 118 modifiedFile A, then merge error detection program 114 flags File A and allsoftware development activities in child code stream 118 that modifiedFile A. Merge error detection program 114 also flags softwaredevelopment activity 204 because software development activity 204contains changes made to File A. Because merge error detection program114 detected a potential merge error, merge error detection program 114cancels the merge of child code stream 118 to main code stream 116, andnone of the changes from child code stream 118 are delivered, regardlessof their merge error status. Merge error detection program 114 notifiesa software developer of the potential merge error. The softwaredeveloper reviews the flagged file and rectifies the error in mergeerror intervention 216. Once the software developer clears the flag onFile A, merge error detection program 114 also removes the flag onsoftware development activity 204 since there are no other filescontained within software development activity 204 that have beenflagged. Furthermore, merge error detection program 114 marks softwaredevelopment activity 204 as reviewed, such that merge error detectionprogram 114 will not re-detect the same activity on subsequent mergeattempts. Once the software developer completes the review of flaggedfiles and activities, the software developer re-attempts the merge ofchild code stream 118 into main code stream 116. Since the softwaredeveloper rectified the missing changes during merge error intervention216, child code stream 118 passes the checks of merge error detectionprogram 114, and version control software 110 completes the stream mergein event 218.

In a second example, the user that triggers rebase 208 intentionallyremoves changes to File A from software development activity 206 duringmerge changes 210. The process proceeds as described with respect to thefirst example, with merge error detection program 114 creating flag 214for File A and software development activity 204, and notifying asoftware developer of the potential merge error. At merge errorintervention 216, the software developer reviews the flags anddetermines that the changes were intentionally removed from File A inchild code stream 118 during merge changes 210. The software developerclears the flag on File A without making any modifications. Merge errordetection program 114 removes the flag on software development activity204 since there are no other files contained within software developmentactivity 204 that have been flagged. Again, merge error detectionprogram 114 marks software development activity 204 as reviewed, suchthat merge error detection program 114 will not re-detect the sameactivity on subsequent merge attempts. Once there are no flagged filesor activities remaining for review, version control software 110 canre-attempt the stream merge in event 218.

When version control software 110 re-attempts the merge of child codestream 118 into main code stream 116 in event 218, merge error detectionprogram 114 again determines that changes to File A in main code stream116 from activity 206 are missing in child code stream 118. Merge errordetection program 114 further determines that the changes were notintentionally removed from child code stream 118 because the deletion ofthe changes was not part of activity 204 or any other non-merge activityon child code stream 118. Merge error detection program 114 then checkswhether File A has any associated activities that have not beenpreviously marked as reviewed. Since activity 204 was marked as reviewedduring merge error intervention 216, merge error detection program 114determines there are no other activities on child code stream 118containing File A that have not been reviewed. Therefore merge errordetection program 114 determines that the missing changes have beenpreviously reviewed and cleared. Since there are no additional missingchanges requiring review, merge error detection program 114 triggersversion control software 110 to complete the stream merge in event 218.

FIG. 3 is a flowchart depicting operational steps of merge errordetection program 114, on server computer 108 within distributed dataprocessing environment 100 of FIG. 1, for detection of source code mergeissues, in accordance with an embodiment of the present invention.

Merge error detection program 114 detects a merge process start (step302). As version control software 110 begins, either automatically or asa result of a prompt or trigger from a software developer, to mergechild code stream 118 into main code stream 116, merge error detectionprogram 114 detects the beginning of a merge process. In one embodiment,merge error detection program 114 may also detect version controlsoftware 110 performing a rebase operation on the child stream justbefore or as part of the beginning of the merge process, as discussedwith respect to FIG. 2. In another embodiment, merge error detectionprogram 114 can trigger a rebase operation prior to step 302.

Merge error detection program 114 compares changes in main code stream116 that were made since the time child code stream 118 branched off, orsince child code stream 118 was last successfully merged with main codestream 116, to incoming child code stream 118 (step 304). At the timechild code stream 118 branches off from main code stream 116, the twocode streams are identical. Once child code stream 118 branches off,software developers update each stream with one or more changes. One ormore rebase operations may be performed between the time of the branchand the time of the merge in order to sync the two code streams, buterrors can be made. At the time when child code stream 118 is to bemerged into main code stream 116, merge error detection program 114compares change sets for files of each software development activitythat has been made to main code stream 116, since the time that childcode stream 118 was branched off or since child code stream 118 was lastsuccessfully merged with main code stream 116, to the correspondingfiles of each software development activity in child code stream 118 toconfirm that none of the changes to main code stream 116 have beeninadvertently removed from child code stream 118. In one embodiment,merge error detection program 114 compares all files changed in maincode stream 116 to the corresponding files in child code stream 118. Inanother embodiment, merge error detection program 114 may compare filesselected by a user of client computing device 104, via user interface106. In yet another embodiment, merge error detection program 114 maycompare files with changes made within a specified period of time, forexample, changes made within the last ten days. In a further embodiment,merge error detection program 114 may compare files changed by aspecific user.

Merge error detection program 114 determines whether any changes made tomain code stream 116 are not included in child code stream 118 (decisionblock 306). After comparing the changes made to main code stream 116 tochild code stream 118, merge error detection program 114 determineswhether any of the previous changes are missing from one or more filesin one or more software development activities within child code stream118. If merge error detection program 114 determines that changes madeto main code stream 116 are not included in child code stream 118 (“yes”branch, decision block 306), then merge error detection program 114determines whether the missing changes were removed from child codestream 118 in a software development activity (decision block 308).

If merge error detection program 114 determines the missing changes werenot removed from child code stream 118 in a software developmentactivity since child code stream 118 branched off or since child codestream 118 was last successfully merged with main code stream 116 (“no”branch, decision block 308), then merge error detection program 114determines whether there are any un-reviewed activities in the childstream that contain a file with the missing changes (decision block309). Merge error detection program 114 considers activities as“un-reviewed” prior to the first merge attempt. In addition, merge errordetection program 114 considers activities that were not deliveredduring a previous merge attempt and were not flagged with potentialconflicts as “un-reviewed.” When merge error detection program 114reaches decision block 309 during a merge re-attempt, merge errordetection program 114 considers previously reviewed activities as“reviewed.”

If merge error detection program 114 determines there are un-reviewedsoftware development activities in the child stream that contain a filewith the missing changes (“yes” branch, decision block 309), then mergeerror detection program 114 flags the conflicts (step 310). If themissing changes were not modified or removed in a software developmentactivity within child code stream 118 since child code stream 118branched off or since child code stream 118 was last successfully mergedwith main code stream 116, and the software development activity isun-reviewed, then merge error detection program 114 determines thechanges may have been removed unintentionally or inadvertently during aprevious merge process. Merge error detection program 114 flags thecorresponding one or more files and the one or more software developmentactivities associated with the flagged files in child code stream 118for later review by a software developer. If multiple softwareactivities in child code stream 118 include the flagged file, then mergeerror detection program 114 flags each activity that includes theflagged file.

Responsive to flagging the conflicts, or responsive to determining themissing changes were removed from child code stream 118 in a softwaredevelopment activity (“yes” branch, decision block 308), or responsiveto determining there are no un-reviewed activities in the child streamthat contain a file with the missing changes (“no” branch, decisionblock 309), merge error detection program 114 determines whether thereis another file for comparison (decision block 312). If the missingchanges were modified or removed in a software development activitywithin child code stream 118, then merge error detection program 114determines the changes were removed intentionally, and merge errordetection program 114 proceeds to determine whether another file orassociated software development activity within main code stream 116needs to be checked for missing changes. In one embodiment, merge errordetection program 114 may review all the files within a particularactivity. Once merge error detection program 114 completes a review ofall files within an activity, merge error detection program 114 mayproceed to review files within another activity.

If merge error detection program 114 determines there is another filefor comparison (“yes” branch, decision block 312), then merge errordetection program 114 returns to step 308. If merge error detectionprogram 114 determines there is not another file or software developmentactivity for comparison (“no” branch, decision block 312), then mergeerror detection program 114 determines whether one or more files andassociated activities have been flagged (decision block 314). Once mergeerror detection program 114 has compared all the changed files andsoftware development activities from main code stream 116 to child codestream 118, merge error detection program 114 reviews the results ofstep 310 to determine whether merge error detection program 114 flaggedany of the comparisons.

If merge error detection program 114 determines one or more files andassociated activities have been flagged (“yes” branch, decision block314), then merge error detection program 114 compiles a list of flaggedfiles and software development activities (step 316). Merge errordetection program 114 compiles a list of all files and softwaredevelopment activities of child code stream 118 that are missing changesthat were made to corresponding files of main code stream 116. Inaddition, merge error detection program 114 may list one or more mergeactivities that contain flagged files.

Merge error detection program 114 sends the list of flagged files andsoftware development activities to a software developer (step 318). Inone embodiment, merge error detection program 114 may preventre-attempts to merge child code stream 118 into main code stream 116until action is taken to remove the flags. In order to alert a softwaredeveloper to potential merge errors, merge error detection program 114may send the list of flagged files and software development activitiesto the software developer, via user interface 106, such that thesoftware developer can review the list and either rectify merge errorsor determine the changes were intentional during a previous merge. Oncean error is either rectified or determined to be intentional, thesoftware developer removes the flag and marks the file and associatedsoftware development activities as reviewed, such that the merge processcan be re-attempted. In one embodiment, the software developer may markan activity as reviewed by manually setting a “reviewed” property inversion control software 110. Merge error detection program 114considers activities included in a failed merge attempt containing noflagged errors as “un-reviewed” on subsequent merge attempts. Activitiesthat have been reviewed retain the reviewed status even if the mergere-attempt fails. Version control software 110 may re-attempt to mergechild code stream 118 into main code stream 116 once no softwaredevelopment activities are flagged. If version control software 110re-attempts to merge child code stream 118 into main code stream 116with flags remaining, then merge error detection program 114 willre-detect the same conflicts. In one embodiment, the software developernotifies version control software 110 that the flags have been removedvia user interface 106.

Responsive to determining there are no changes made to main code stream116 that are not included in child code stream 118 (“no” branch,decision block 306), or responsive to determining no files have beenflagged (“no” branch, decision block 314), merge error detection program114 triggers the merge (step 320). If merge error detection program 114does not detect any potential merge errors, then merge error detectionprogram 114 triggers version control software 110 to proceed withmerging child code stream 118 into main code stream 116.

In one embodiment, if merge error detection program 114 had previouslycompared main code stream 116 to child code stream 118, then merge errordetection program 114 may perform an additional step prior to step 304in which merge error detection program 114 determines whether files oractivities that had been flagged during a previous comparison have beencleared of the flags or if the files remain flagged. If merge errordetection program 114 determines that previous flags have not beencleared, then merge error detection program 114 may stop the mergeprocess and notify a software developer, via user interface 106, toclear previous flags in order to proceed with the merge process. Ifmerge error detection program 114 determines that previous flags havebeen cleared, then merge error detection program 114 may continue withstep 304.

FIG. 4 depicts a block diagram of components of server computer 108within distributed data processing environment 100 of FIG. 1, inaccordance with an embodiment of the present invention. It should beappreciated that FIG. 4 provides only an illustration of oneimplementation and does not imply any limitations with regard to theenvironments in which different embodiments can be implemented. Manymodifications to the depicted environment can be made.

Server computer 108 can include processor(s) 404, cache 414, memory 406,persistent storage 408, communications unit 410, input/output (I/O)interface(s) 412 and communications fabric 402. Communications fabric402 provides communications between cache 414, memory 406, persistentstorage 408, communications unit 410, and input/output (I/O)interface(s) 412. Communications fabric 402 can be implemented with anyarchitecture designed for passing data and/or control informationbetween processors (such as microprocessors, communications and networkprocessors, etc.), system memory, peripheral devices, and any otherhardware components within a system. For example, communications fabric402 can be implemented with one or more buses.

Memory 406 and persistent storage 408 are computer readable storagemedia. In this embodiment, memory 406 includes random access memory(RAM). In general, memory 406 can include any suitable volatile ornon-volatile computer readable storage media. Cache 414 is a fast memorythat enhances the performance of processor(s) 404 by holding recentlyaccessed data, and data near recently accessed data, from memory 406.

Program instructions and data used to practice embodiments of thepresent invention, e.g., version control software 110, version controldatabase 112, merge error detection program 114, main code stream 116,and child code stream 118 can be stored in persistent storage 408 forexecution and/or access by one or more of the respective processor(s)404 of server computer 108 via memory 406. In this embodiment,persistent storage 408 includes a magnetic hard disk drive.Alternatively, or in addition to a magnetic hard disk drive, persistentstorage 408 can include a solid-state hard drive, a semiconductorstorage device, a read-only memory (ROM), an erasable programmableread-only memory (EPROM), a flash memory, or any other computer readablestorage media that is capable of storing program instructions or digitalinformation.

The media used by persistent storage 408 may also be removable. Forexample, a removable hard drive may be used for persistent storage 408.Other examples include optical and magnetic disks, thumb drives, andsmart cards that are inserted into a drive for transfer onto anothercomputer readable storage medium that is also part of persistent storage408.

Communications unit 410, in these examples, provides for communicationswith other data processing systems or devices, including resources ofclient computing device 104. In these examples, communications unit 410includes one or more network interface cards. Communications unit 410may provide communications through the use of either or both physicaland wireless communications links. Version control software 110, versioncontrol database 112, merge error detection program 114, main codestream 116, and child code stream 118 may be downloaded to persistentstorage 408 of server computer 108 through communications unit 410.

I/O interface(s) 412 allows for input and output of data with otherdevices that may be connected to server computer 108. For example, I/Ointerface(s) 412 may provide a connection to external device(s) 416 suchas a keyboard, a keypad, a touch screen, a microphone, a digital camera,and/or some other suitable input device. External device(s) 416 can alsoinclude portable computer readable storage media such as, for example,thumb drives, portable optical or magnetic disks, and memory cards.Software and data used to practice embodiments of the present invention,e.g., version control software 110, version control database 112, mergeerror detection program 114, main code stream 116, and child code stream118 on server computer 108, can be stored on such portable computerreadable storage media and can be loaded onto persistent storage 408 viaI/O interface(s) 412. I/O interface(s) 412 also connect to a display418.

Display 418 provides a mechanism to display data to a user and may be,for example, a computer monitor. Display 418 can also function as atouchscreen, such as a display of a tablet computer.

The programs described herein are identified based upon the applicationfor which they are implemented in a specific embodiment of theinvention. However, it should be appreciated that any particular programnomenclature herein is used merely for convenience, and thus theinvention should not be limited to use solely in any specificapplication identified and/or implied by such nomenclature.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be any tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, a special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, a segment, or aportion of instructions, which comprises one or more executableinstructions for implementing the specified logical function(s). In somealternative implementations, the functions noted in the blocks may occurout of the order noted in the Figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method for detection of potential merge errorswhen merging source code, the method comprising: detecting, by one ormore computer processors, a source code merge process start;determining, by the one or more computer processors, whether one or moreof at least one change made to a main stream of source code werepreviously compared to a first child stream, wherein the first childstream is an incoming child stream of source code; responsive todetermining the one or more of the at least one change made to the mainstream of source code were previously compared to the first childstream, determining, by the one or more computer processors, whether oneor more files of the first child stream corresponding to the one or moreof the at least one change were flagged during the previous comparison;responsive to determining one or more files of the first child streamcorresponding to the one or more of the at least one change were flaggedduring the previous comparison, determining, by the one or more computerprocessors, whether the one or more files remain flagged; responsive todetermining the one or more files do not remain flagged, comparing, bythe one or more computer processors, the at least one change made to themain stream of source code to the first child stream, and wherein the atleast one change was made between a time corresponding to a branching ofthe first child stream and a time of the merge process start;determining, by the one or more computer processors, whether one or moreof the at least one change made to the main stream of source code arenot included in the first child stream; responsive to determining one ormore of the at least one change made to the main stream of source codeare not included in the first child stream, determining, by the one ormore computer processors, whether the one or more of the at least onechange made to the main stream of source code that are not included inthe first child stream were removed from the first child stream during asoftware development activity; and responsive to determining the one ormore of the at least one change made to the main stream of source codethat are not included in the first child stream were not removed fromthe first child stream during a software development activity, flagging,by the one or more computer processors, one or more files of the firstchild stream corresponding to the one or more of the at least onechange.
 2. The method of claim 1, further comprising: responsive toflagging one or more files of the first child stream corresponding tothe one or more of the at least one change, compiling, by the one ormore computer processors, a list of the one or more flagged files; andsending, by the one or more computer processors, the list to a user. 3.The method of claim 1, wherein flagging one or more files of the firstchild stream corresponding to the one or more of the at least one changefurther comprises flagging, by the one or more computer processors, atleast one of: a change, a file corresponding to a change, or a softwaredevelopment activity corresponding to a change.
 4. The method of claim1, further comprising, responsive to determining the one or more of theat least one change made to the main stream of source code that are notincluded in the first child stream were removed from the first childstream during a software development activity, triggering, by the one ormore computer processors, a merge process.
 5. The method of claim 1,further comprising, responsive to determining one or more of the atleast one change made to the main stream of source code are included inthe first child stream, triggering, by the one or more computerprocessors, a merge process.
 6. The method of claim 1, furthercomprising, prior to detecting the source code merge process start,triggering, by the one or more computer processors, a rebase operationon the first child stream.
 7. The method of claim 1, further comprising:responsive to determining the one or more of the at least one changemade to the main stream of source code that are not included in thefirst child stream were not removed from the first child stream during asoftware development activity, determining, by the one or more computerprocessors, whether one or more software development activities in thefirst child stream containing a file that does not include the at leastone change made to the main stream of source code has been reviewed; andresponsive to determining one or more software development activities inthe first child stream containing a file that does not include the atleast one change made to the main stream of source code has not beenreviewed, flagging, by the one or more computer processors, one or morefiles of the first child stream corresponding to the one or more atleast one change.
 8. A computer program product for detection ofpotential merge errors when merging source code, the computer programproduct comprising: one or more computer readable storage devices andprogram instructions stored on the one or more computer readable storagedevices, the stored program instructions comprising: programinstructions to detect a source code merge process start; programinstructions to determine whether one or more of at least one changemade to a main stream of source code were previously compared to a firstchild stream, wherein the first child stream is an incoming child streamof source code; responsive to determining the one or more of the atleast one change made to the main stream of source code were previouslycompared to the first child stream, program instructions to determinewhether one or more files of the first child stream corresponding to theone or more of the at least one change were flagged during the previouscomparison; responsive to determining one or more files of the firstchild stream corresponding to the one or more of the at least one changewere flagged during the previous comparison, program instructions todetermine whether the one or more files remain flagged; responsive todetermining the one or more files do not remain flagged, programinstructions to compare at least one change made to a main stream ofsource code to a first child stream, wherein the first child stream isan incoming child stream of source code, and wherein the at least onechange was made between a time corresponding to a branching of the firstchild stream and a time of the merge process start; program instructionsto determine whether one or more of the at least one change made to themain stream of source code are not included in the first child stream;responsive to determining one or more of the at least one change made tothe main stream of source code are not included in the first childstream, program instructions to determine whether the one or more of theat least one change made to the main stream of source code that are notincluded in the first child stream were removed from the first childstream during a software development activity; and responsive todetermining the one or more of the at least one change made to the mainstream of source code that are not included in the first child streamwere not removed from the first child stream during a softwaredevelopment activity, program instructions to flag one or more files ofthe first child stream corresponding to the one or more of the at leastone change.
 9. The computer program product of claim 8, the storedprogram instructions further comprising: responsive to flagging one ormore files of the first child stream corresponding to the one or more ofthe at least one change, program instructions to compile a list of theone or more flagged files; and program instructions to send the list toa user.
 10. The computer program product of claim 8, the stored programinstructions further comprising, responsive to determining the one ormore of the at least one change made to the main stream of source codethat are not included in the first child stream were removed from thefirst child stream during a software development activity, programinstructions to trigger a merge process.
 11. The computer programproduct of claim 8, the stored program instructions further comprising,responsive to determining one or more of the at least one change made tothe main stream of source code are included in the first child stream,program instructions to trigger a merge process.
 12. The computerprogram product of claim 8, the stored program instructions furthercomprising: responsive to determining the one or more of the at leastone change made to the main stream of source code that are not includedin the first child stream were not removed from the first child streamduring a software development activity, program instructions todetermine whether one or more software development activities in thefirst child stream containing a file that does not include the at leastone change made to the main stream of source code has been reviewed; andresponsive to determining one or more software development activities inthe first child stream containing a file that does not include the atleast one change made to the main stream of source code has not beenreviewed, program instructions to flag one or more files of the firstchild stream corresponding to the one or more at least one change. 13.The computer program product of claim 8, the stored program instructionsfurther comprising: responsive to detecting a source code merge processstart, program instructions to determine whether one or more of the atleast one change made to the main stream of source code were previouslycompared to the first child stream; responsive to determining the one ormore of the at least one change made to the main stream of source codewere previously compared to the first child stream, program instructionsto determine whether one or more files of the first child streamcorresponding to the one or more of the at least one change were flaggedduring a previous comparison; responsive to determining one or morefiles of the first child stream corresponding to the one or more of theat least one change were flagged during the previous comparison, programinstructions to determine whether the one or more files remain flagged;and responsive to determining the one or more files remain flagged,program instructions to notify a user.
 14. A method for detection ofpotential merge errors when merging source code, the method comprising:detecting, by one or more computer processors, a source code mergeprocess start; determining, by the one or more computer processors,whether one or more of at least one change made to a main stream ofsource code were previously compared to a first child stream, whereinthe first child stream is an incoming child stream of source code;responsive to determining the one or more of the at least one changemade to the main stream of source code were previously compared to thefirst child stream, determining, by the one or more computer processors,whether one or more files of the first child stream corresponding to theone or more of the at least one change were flagged during a previouscomparison; responsive to determining one or more files of the firstchild stream corresponding to the one or more of the at least one changewere flagged during the previous comparison, determining, by the one ormore computer processors, whether the one or more files remain flagged;and responsive to determining the one or more files remain flagged,notifying, by the one or more computer processors, a user.